Design of Direct 48-V/1-V Three-Path Four-State Switching Power Converter With Adaptive V<sub>CF</sub> Rebalancing and Dual-Edge t<sub>dead</sub> Modulation
Yuanqing Huang, Yogesh Ramadass, D. Brian
Abstract
This article presents a new power converter capable of direct 48-V/1-V dc–dc conversion with high efficiency. The proposed three-path four-state (3P4S) hybrid switching power stage enables high switching frequency ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f_{\mathrm {SW}}$ </tex-math></inline-formula> ) operation and minimizes power passives by significantly reducing power switch voltage stress. To address the issues of power delivery path imbalances and potential device breakdown, an adaptive flying capacitor voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\mathrm {CF}}$ </tex-math></inline-formula> ) rebalancing technique is introduced that improves design robustness and eliminates the need for direct floating <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\mathrm {CF}}$ </tex-math></inline-formula> sensing. Additionally, a dual-edge deadtime ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$t_{\mathrm {dead}}$ </tex-math></inline-formula> ) modulation with elastic <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$t_{\mathrm {dead}}$ </tex-math></inline-formula> control at switching nodes optimizes converter efficiency across different input voltage and load conditions. An IC prototype of the design was fabricated and tested with input voltage <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\mathrm {IN}}$ </tex-math></inline-formula> ranging from 12 to 48 V, delivering up to 4 W of power at 1-V <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\mathrm {O}}$ </tex-math></inline-formula> . It achieves peak efficiency of 90.7% and 85.6% for 12-V/1-V and 48-V/1-V power conversion, respectively, at an effective switching frequency of 4.5 MHz, which is based on a three-phase operation with each phase at 1.5 MHz. The adaptive <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\mathrm {CF}}$ </tex-math></inline-formula> rebalancing technique reduces <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\mathrm {CF}}$ </tex-math></inline-formula> imbalance error by up to 65.1%. Overall, the proposed 3P4S hybrid switching power converter offers an efficient and robust solution for direct dc–dc conversion with a wide <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\mathrm {IN}}$ </tex-math></inline-formula> range.